β Scribed by Mark C. Piton; Alison J. Lennon; Bogdan E. Chapman; Philip W. Kuchel
No coin nor oath required. For personal study only.
Pulsed field gradient (PFG) NMR spectroscopy was used to measure the translational diffusion coefficient of solvent toluene in spheres made from polystyrene (latex). The latex spheres had a bimodal size distribution that was measured using transmission electron microscopy and image analysis. Analysis of the PFG data using the equations of Murday and Cotts (J. Chem. Phys. 48, 4938, 1968) for diffusion restricted to a sphere demonstrated the need, in general, to incorporate the entire size distribution of the latex particles into the analysis when the particle sizes are sufficiently polydisperse. The values of self-diffusion coefficients obtained from this analysis were significantly higher than those predicted by bulk diffusion studies. This discrepancy could not be attributed to an inaccuracy in the approximation, inherent in the Murday and Cotts equations, that the distribution of the phases of the magnetization vectors confined to a sphere is Gaussian and could suggest the presence of heterogeneities within the latex particles. 1994 Academic Press, Inc.
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Most analyses of submicron particles using sedimentation field-flow Ε½ . fractionation SdFFF have been carried out in aqueous systems. However, a nonaqueous carrier solution could be suitable for SdFFF when the particle density is close to the density of water. Few papers have reported the retention
A steady-state fluorescence technique was used to examine the annealing of films formed from high-T latex particles above the glass transition temperature. The films were prepared by sintering pyrene-labeled poly(methy1 methacrylate) latex particles. During the annealing processes, the transparency